[timo614]

You can still buy it as part of a controller bundle for now: http://www.amazon.com/Microsoft-Xbox-Wireless-Controller-Win...

Not sure if Amazon is just working through the remainder of their stock though if it is discontinued (they're listed as a seller on the right since some third part one is like a dime cheaper). I never was able to find the Microsoft dongle alone without the controller though so perhaps they did discontinue it.

Not a bad price for both the dongle and a controller though and always nice to have another one for when friends stop by for some Sonic Racing.